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Superfund Alternative Site For Wisconsin
MANITOWOC COUNTY
MANITOWOC
Congressional District # 06
WPSC MANITOWOC MGP
EPA ID# WIN000509949Last Updated: February, 2007
Site Description
The WPSC Manitowoc MGP site is located in Manitowoc, Wisconsin. Wisconsin Public Service Corporation (WPSC), an operating utility company, is responsible for several former manufactured gas plants (MGPs) throughout Wisconsin. The Manitowoc facility is about 4 acres in size, with approximately 1.2 additional acres of contaminated adjacent sediment. The Manitowoc site is located in an historically industrial area. Operation records are not complete, but the gas plant seems to have operated from before 1900 to about 1947. The Manitowoc River borders the site on the northwest. Currently the majority of the site is occupied by actively used commercial buildings and asphalt parking lots. Residential, commercial and industrial use properties are found in the vicinity of the site.
MGPs were industrial facilities that produced gas from coal, oil, and other feedstocks. MGPs started operating in the U.S. in the early 1800s, typically in urban areas where gas was needed for lighting, cooking, and heating. Two gas production methods were used at the WPSC MGP facilities: coal carbonization and carbureted water gas. Both processes produced waste and by-products such as tars, purifier waste, oils, sludges, and acidic waste. Disposal of waste and spills and leaks often resulted in contaminated soil and groundwater. MGPs were often located near waterbodies and sediment contamination is also common.
Site Responsibility
This site is being addressed through federal and potentially responsible party actions. This is one of six former MGPs to be addressed by WPSC under the Superfund Alternative Sites approach.
Threats and Contaminants
Soil, groundwater and sediment at former MGPs are often contaminated. At the Manitowoc site soil cleanup was conducted on the most contaminated areas. However, soil at the site still contains residuals of polynuclear aromatic hydrocarbons (PAHs); volatile organic compounds (VOCs), especially a group of VOCs called benzene, toluene, ethylbenzene, and xylene (BTEX); and cyanide. Groundwater flows generally from the site towards the Manitowoc River. Groundwater contamination includes PAHs; cyanide; napthalene; benzo(a)pyrene; trimethylbenzene; and BTEX. Free product (DNAPL) is routinely found in an area near the southwest corner of one of the buildings. Sediment is the nearby Manitowoc River contain PAHs and BTEX, and shows evidence of odor, sheen or tar associated with MGP waste. Visible sheens have been observed in surface water near the site.
Cleanup Progress
WPSC and EPA entered a settlement agreement in May 2006. Under this unique agreement, WPSC has agreed to conduct remedial investigations and feasibility studies at six former MGP sites located throughout Wisconsin. Because the six sites have similar conditions and contaminants, and WPSC is responsible for each, the agreement allows a streamlined approach to site investigation and remedy development. Some benefits of the agreement include the use of multi-site documents, a mechanism to review the adequacy of past work, and scheduling flexibility to allow progress on the worst problems first.
Under the state program various investigations of the Manitowoc site have occurred since 1988. Some upland cleanup occured between 1992 to 1994 when highly contaminated soil between the WPSC building and the Manitowoc River was excavated and removed from the site or treated in place by stabilization. Routine groundwater monitoring occurs annually. In 1997 a single extraction well and treatment system were installed to address the free product found in groundwater. Additional investigation of remaining contamination will occur under the enforcement agreement with EPA. Work planning began in late 2006.